etcdutil, server: sort out the initialization functions of etcd client (

#7725)

ref #7499

Sort out the initialization functions of etcd client.

Signed-off-by: JmPotato <ghzpotato@gmail.com>

pkg/mcs/utils/util.go

@@ -177,12 +177,12 @@ func InitClient(s server) error {
 	if err != nil {
 		return err
 	}
-	etcdClient, httpClient, err := etcdutil.CreateClients(tlsConfig, backendUrls)
+	etcdClient, err := etcdutil.CreateEtcdClient(tlsConfig, backendUrls)
 	if err != nil {
 		return err
 	}
 	s.SetETCDClient(etcdClient)
-	s.SetHTTPClient(httpClient)
+	s.SetHTTPClient(etcdutil.CreateHTTPClient(tlsConfig))
 	return nil
 }
 

pkg/utils/etcdutil/etcdutil.go

@@ -460,18 +460,8 @@ func syncUrls(client *clientv3.Client) []string {
 	return eps
 }
 
-// CreateClients creates etcd v3 client and http client.
-func CreateClients(tlsConfig *tls.Config, acUrls []url.URL) (*clientv3.Client, *http.Client, error) {
-	client, err := CreateEtcdClient(tlsConfig, acUrls)
-	if err != nil {
-		return nil, nil, errs.ErrNewEtcdClient.Wrap(err).GenWithStackByCause()
-	}
-	httpClient := createHTTPClient(tlsConfig)
-	return client, httpClient, nil
-}
-
-// createHTTPClient creates a http client with the given tls config.
-func createHTTPClient(tlsConfig *tls.Config) *http.Client {
+// CreateHTTPClient creates a http client with the given tls config.
+func CreateHTTPClient(tlsConfig *tls.Config) *http.Client {
 	// FIXME: Currently, there is no timeout set for certain requests, such as GetRegions,
 	// which may take a significant amount of time. However, it might be necessary to
 	// define an appropriate timeout in the future.

server/server.go

@@ -348,36 +348,16 @@ func (s *Server) startEtcd(ctx context.Context) error {
 		return errs.ErrCancelStartEtcd.FastGenByArgs()
 	}
 
-	// start client
-	s.client, s.httpClient, err = s.startClient()
+	// Start the etcd and HTTP clients, then init the member.
+	err = s.startClient()
 	if err != nil {
 		return err
 	}
-
-	s.electionClient, err = s.startElectionClient()
+	err = s.initMember(etcd)
 	if err != nil {
 		return err
 	}
 
-	// update advertise peer urls.
-	etcdMembers, err := etcdutil.ListEtcdMembers(s.client)
-	if err != nil {
-		return err
-	}
-	etcdServerID := uint64(etcd.Server.ID())
-	for _, m := range etcdMembers.Members {
-		if etcdServerID == m.ID {
-			etcdPeerURLs := strings.Join(m.PeerURLs, ",")
-			if s.cfg.AdvertisePeerUrls != etcdPeerURLs {
-				log.Info("update advertise peer urls", zap.String("from", s.cfg.AdvertisePeerUrls), zap.String("to", etcdPeerURLs))
-				s.cfg.AdvertisePeerUrls = etcdPeerURLs
-			}
-		}
-	}
-	failpoint.Inject("memberNil", func() {
-		time.Sleep(1500 * time.Millisecond)
-	})
-	s.member = member.NewMember(etcd, s.electionClient, etcdServerID)
 	s.initGRPCServiceLabels()
 	return nil
 }
@@ -392,29 +372,51 @@ func (s *Server) initGRPCServiceLabels() {
 	}
 }
 
-func (s *Server) startClient() (*clientv3.Client, *http.Client, error) {
+func (s *Server) startClient() error {
 	tlsConfig, err := s.cfg.Security.ToTLSConfig()
 	if err != nil {
-		return nil, nil, err
+		return err
 	}
 	etcdCfg, err := s.cfg.GenEmbedEtcdConfig()
 	if err != nil {
-		return nil, nil, err
+		return err
 	}
-	return etcdutil.CreateClients(tlsConfig, etcdCfg.ACUrls)
-}
-
-func (s *Server) startElectionClient() (*clientv3.Client, error) {
-	tlsConfig, err := s.cfg.Security.ToTLSConfig()
+	/* Starting two different etcd clients here is to avoid the throttling. */
+	// This etcd client will be used to access the etcd cluster to read and write all kinds of meta data.
+	s.client, err = etcdutil.CreateEtcdClient(tlsConfig, etcdCfg.ACUrls)
 	if err != nil {
-		return nil, err
+		return errs.ErrNewEtcdClient.Wrap(err).GenWithStackByCause()
 	}
-	etcdCfg, err := s.cfg.GenEmbedEtcdConfig()
+	// This etcd client will only be used to read and write the election-related data, such as leader key.
+	s.electionClient, err = etcdutil.CreateEtcdClient(tlsConfig, etcdCfg.ACUrls)
 	if err != nil {
-		return nil, err
+		return errs.ErrNewEtcdClient.Wrap(err).GenWithStackByCause()
 	}
+	s.httpClient = etcdutil.CreateHTTPClient(tlsConfig)
+	return nil
+}
 
-	return etcdutil.CreateEtcdClient(tlsConfig, etcdCfg.ACUrls)
+func (s *Server) initMember(etcd *embed.Etcd) error {
+	// Update advertise peer URLs.
+	etcdMembers, err := etcdutil.ListEtcdMembers(s.client)
+	if err != nil {
+		return err
+	}
+	etcdServerID := uint64(etcd.Server.ID())
+	for _, m := range etcdMembers.Members {
+		if etcdServerID == m.ID {
+			etcdPeerURLs := strings.Join(m.PeerURLs, ",")
+			if s.cfg.AdvertisePeerUrls != etcdPeerURLs {
+				log.Info("update advertise peer urls", zap.String("from", s.cfg.AdvertisePeerUrls), zap.String("to", etcdPeerURLs))
+				s.cfg.AdvertisePeerUrls = etcdPeerURLs
+			}
+		}
+	}
+	failpoint.Inject("memberNil", func() {
+		time.Sleep(1500 * time.Millisecond)
+	})
+	s.member = member.NewMember(etcd, s.electionClient, etcdServerID)
+	return nil
 }
 
 // AddStartCallback adds a callback in the startServer phase.